Body Temperature Fluctuation After Ovariohysterectomy in Dogs in Luteal Phase, Inactive Phase and Pyometra: A Clinical Study of 77 Cases.

Progesterone (P4) has a thermogenic effect in the bitch and a decrease in P4 has been associated with a mild transient decrease in body temperature. The aim of this study was to investigate the presence, the extent and the pattern of possible hypothermia after ovariohysterectomy (OHE) in healthy dogs in luteal phase and in bitches with pyometra that underwent therapeutic OHE. Sixty-two healthy dogs and 15 dogs with pyometra that underwent standardized OHE were included. Rectal temperature was measured 1 hour preoperatively (pre-op) and 6, 9, 12, 18, 24, 30, 36, 42, and 48 hours postoperatively (post-op). Serum P4 was measured 30 minutes pre-op and 6 and 24 hours post-op. Healthy dogs were classified in 3 groups based on their initial P4 concentration and in 3 separate groups based on their oestrus cycle stage. The temperature differentiation between the groups of the study was assessed using the repeated measures mixed-design ANOVA analysis. Temperature measured 18-42 hours post-op was significantly decreased compared to pre-op when initial P4 >8 ng/mL but not significantly decreased when P4 <8 ng/mL. Post-op temperature fluctuation in pregnant dogs showed no significant difference compared to dogs in diestrus. Dogs with pyometra had significantly lower temperature 6-48 hours post-op compared to all other groups. Conclusively, mild hypothermia (37.5-37.9°C) may be anticipated 18-42 hours after OHE performed in early diestrus or pregnancy in healthy dogs. More significant hypothermia (37.1-37.5°C) may be anticipated in normally recovering pyometra cases.